Implementers of engine control schemes face continued requirements to improve fuel economy and reduce quantities of various emissions constituents, including hydrocarbons, carbon monoxide, carbon dioxide, and nitrides of oxygen (NOx). One engine configuration and control strategy comprises a spray-guided spark-ignited direct-injection gasoline engine to realize better combustion stability, better fuel economy and lower emissions. A main benefit of an engine employing spray-guided fuel injection is improved fuel economy, because the engine is operable at a lean fuel/air equivalence ratio at low-to-medium engine loads and at low-to-medium engine speeds. However such operation may affect combustion stability of the engine.
Various fuel injection and ignition system designs and control strategies have been shown to improve combustion stability, resulting in improved fuel economy and lower combustion emissions. Exemplary methods include: a wider or narrower injector spray cone, a higher or lower injection rate, and, a spark-plug gap that is located inside, on the edge, or outside the fuel spray cone. Current injection and ignition strategies wherein fuel is completely injected before ignition suffer from poor combustion stability, which can result in increases in emissions, fuel consumption, and smoke.
There is a need to provide an improved strategy to address the concerns mentioned hereinabove.